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# Aug 24, 2018

Python has two handy functions for creating lists, or a range of integers that assist in making for loops.These functions are xrange and range. But you probably already guessed that! 🙂

### The Difference Between `xrange` and `range` in Python

Before we get started, let's talk about what makes `xrange` and `range` different.

For the most part, `xrange` and `range` are the exact same in terms of functionality. They both provide a way to generate a list of integers for you to use, however you please. **The only difference is that `range` returns a Python `list` object and `xrange` returns an `xrange` object.**

What does that mean? Good question! It means that `xrange` doesn't actually generate a static list at run-time like `range` does. It creates the values as you need them with a special technique called ***yielding***. This technique is used with a type of object known as ***generators***. If you want to read more in depth about generators and the yield keyword, be sure to checkout the article [Python generators and the yield keyword](https://www.pythoncentral.io/python-generators-and-yield-keyword/).

Okay, now what does *that* mean? Another good question. *That* means that **if you have a really gigantic range you'd like to generate a list for, say one billion,** `xrange` **is the function to use**. This is especially true if you have a really memory sensitive system such as a cell phone that you are working with, as `range` will **use as much memory as it can to create your array of integers, which can result in a** `MemoryError` **and crash your program.** It's a memory hungry beast.

That being said, if you'd like to iterate over the list multiple times, it's probably better to use `range`. This is because `xrange` has to generate an integer object every time you access an index, whereas `range` is a static list and the integers are already "there" to use.